Mice do not accumulate muscle lipid in response to dietary conjugated linoleic acid

Dietary CLA decreases body fat in several species and in pigs this is accompanied by increased muscle lipid. Our objective was to determine if mice could be used as a model for CLA-induced increased marbling in pigs. We used our model of enhanced CLA response, where mice fed coconut oil (CO) lose more body fat than mice fed soy oil (SO). Mice (21 d old; Imprinting Control Region [ICR]) were fed SO or CO diets for 6 wk followed by 12 d of 0 or 0.5% mixed isomer CLA. Ether extraction determined that thigh muscle lipid content was reduced by both CLA and CO (P = 0.007 and P = 0.006, respectively). Conjugated linoleic acid also caused a reduction (P = 0.016) in carnitine palmitoyltransferase (CPT) enzyme activity, so less fatty acid oxidation appeared to be occurring. Lumbar muscle, which is more similar to the longissimus dorsi tested in pigs, did not differ in lipid content between mice (56 d old; ICR) fed SO or SO+CLA for 14 d. Therefore, CLA-fed mice do not appear to be accumulating excess lipid in their muscle. However, CLA addition to CO diets increased (P = 0.007) the mRNA expression of PPAR-γ in the thigh muscle to the level of SO-fed mice, indicating that intramuscular adipocyte differentiation may be increasing. On the other hand, liver lipid was increased (P < 0.0001) by CO and tended to be increased (P = 0.099) by CLA. Liver CPT activity was decreased (P = 0.018) in SO+CLA-fed mice but not CO+CLA. It appears that mice may accumulate lipid in their livers preferentially over muscle when fed CLA and therefore are not a good model for CLA-induced muscle lipid accumulation.

Tissue distribution of indices of lysine catabolism in growing swine

The primary pathway of lysine degradation in pigs presumably depends on the bifunctional protein α-aminoadipate δ-semialdehyde synthase (AASS), which contains lysine α-ketoglutarate reductase (LKR) and saccharopine dehydrogenase (SDH) activities. In liver, AASS is restricted to the mitochondrial matrix and lysine is presumptively transported through the plasma membrane by a cationic AA transporter (CAT1/2) and through the inner mitochondrial membrane by 1 or both mitochondrial ornithine transporters (ORC-1/ORC-2). Lysyl oxidase (LO) may represent an alternative pathway of lysine oxidation. The objective of this experiment was to analyze the distribution of indices of lysine catabolism in various pig tissues. We assessed LKR, SDH, and LO activities, lysine oxidation, mRNA abundance of LKR, CAT1/2, and ORC1/2, and AASS protein abundance (via SDH antibody) in liver, heart, kidney medulla and cortex, triceps, longissimus, whole intestine, enterocytes, and intestine stripped of enterocytes in 10 growing pigs, weighing ∼25 kg. The LKR activity differed across tissues (P<0.001) and was greatest in liver, intestine, and kidney samples, and LKR mRNA abundance (P<0.001) was greatest in liver; although, LKR activity and mRNA abundance were detected in all other tissues. Activity of SDH (P<0.001) and SDH mRNA abundance (P<0.001) were affected by tissue and were greatest in liver compared with all other tissues analyzed. The AASS protein abundance (P<0.001) was greatest in whole intestine and liver. Activity of LO (P<0.0001) was greatest in muscle samples. The abundance of ORC-1 (P<0.001) and ORC-2 mRNA (P<0.001) differed among tissues, and ORC-1 was greatest in liver, kidney, and intestinal preparations, and ORC-2 mRNA abundance was greatest in liver and intestine. Interestingly, LKR activity was correlated with ORC-1 (r=0.32, P<0.05) and ORC-2 (r=0.41, P<0.05) expression. The expression of CAT-1 was uniform in all tissues, whereas CAT-2 (P<0.01) was greatest in liver. In conclusion, these data indicate that extra-hepatic tissues contribute to lysine catabolism as do enzymes other than LKR.

Effect of dietary conjugated linoleic acid on marbling and intramuscular adipocytes in pork

Dietary CLA has been reported to decrease backfat and increase marbling in pigs. Our objective was to determine whether the increase in marbling involved changes in intramuscular adipocyte number or size or both. Twenty barrows (53 kg) were penned in pairs and pens were randomly assigned to receive diets containing either 1% soybean oil (SBO) or CLA (60% CLA isomers) for 6 wk. Body weight and feed intake were determined weekly. At slaughter, loin samples were obtained and flash frozen for RNA extraction and real-time reverse-transcription PCR analysis of gene expression. After a 24-h chill, loin eye area and backfat depth were measured and subjective marbling and color scores were assigned. Loin, backfat, and belly fat samples were obtained for fatty acid analysis by gas chromatography. Loin samples were also frozen in ice-cold isopentane for histological analysis of intramuscular adipocytes. Dietary CLA did not affect BW or feed intake at any point (P > 0.10), nor did treatment groups differ in HCW (P = 0.417) or loin color (P = 0.500). The CLA-fed pigs did have less (P = 0.018) backfat and smaller (P = 0.047) loin eye area than SBO-fed pigs and had a trend for an increase (P = 0.069) in marbling score. Relative gene expression for markers of preadipocytes (preadipocyte factor 1; Pref-1), differentiating adipocytes (PPARγ), and mature adipocytes [fatty acid binding protein 4 (FABP4) and perilipin (PLIN)] were determined and normalized to the expression of acidic ribosomal phosphoprotein. No significant differences were detected, but the expression of PPARγ (P = 0.265), PLIN (P = 0.265), and FABP4 (P = 0.148) was numerically greater in CLA-fed pigs than in SBO-fed pigs. Loin samples were stained with Oil Red O to identify intramuscular adipocytes. The average cell area was increased (P = 0.030) in CLA-fed pigs. The cis-9,trans-11 and trans-10,cis-12 CLA isomers were incorporated (P = 0.006) into backfat and belly fat, but only trans-10,cis-12 CLA was increased in the loin (P = 0.004) of CLA-fed pigs. The proportion of SFA was increased (P = 0.006) by CLA in all tissues. These results indicate that the increase in marbling in pigs fed CLA may be related to increased intramuscular adipocyte size, and the combination of increased marbling and degree of saturation could improve the eating quality of CLA-fed pork.

An assessment of the antibacterial activity in larval excretion/secretion of four species of insects recorded in association with corpses, using Lucilia sericata Meigen as the marker species

The relative antibacterial activities of excretion/secretion (ES) from two carrion-feeding insects, Calliphora vicina Robineau-Desvoidy and Dermestes maculatus DeGeer, and a detritivore, Tenebrio molitor Linnaeus, were compared to that of Lucilia sericata Meigen, a species with ES of known antibacterial capacity, in order to explore the antimicrobial potential of other carrion and detritivore species. Viable counts were used to assess time-kill of ES against five bacterial species, Staphylococcus aureus, Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa and Proteus mirabilis. Antibacterial activity was recorded in all four insect species although T. molitor and D. maculatus were the most effective in controlling growth of P. mirabilis. The blowflies were more effective in controlling a wider range of both Gram-positive and Gram-negative bacteria. The larval ES from all species was shown to reduce bacterial growth rate although differences in antibacterial spectrum were noted and the degree of potency varied between the four species. These differences may be explained ecologically by the different colonisation times of each insect species on the corpse. Overall, this study demonstrates that research into other carrion-feeding insect species has potential to provide an increased source of antimicrobial chemicals to broaden the range of bacterial species beyond that currently controlled using L. sericata.

Board-invited review: the biology and regulation of preadipocytes and adipocytes in meat animals

The quality and value of the carcass in domestic meat animals are reflected in its protein and fat content. Preadipocytes and adipocytes are important in establishing the overall fatness of a carcass, as well as being the main contributors to the marbling component needed for consumer preference of meat products. Although some fat accumulation is essential, any excess fat that is deposited into adipose depots other than the marbling fraction is energetically unfavorable and reduces efficiency of production. Hence, this review is focused on current knowledge about the biology and regulation of the important cells of adipose tissue: preadipocytes and adipocytes.

Spatial and temporal regulation of GH-IGF-related gene expression in growth plate cartilage

Previous studies of the GH-IGF system gene expression in growth plate using immunohistochemistry and in situ hybridization have yielded conflicting results. We therefore studied the spatial and temporal patterns of mRNA expression of the GH-IGF system in the rat proximal tibial growth plate quantitatively. Growth plates were microdissected into individual zones. RNA was extracted, reverse transcribed and analyzed by real-time PCR. In 1-week-old animals, IGF-I mRNA expression was minimal in growth plate compared with perichondrium, metaphyseal bone, muscle, and liver (70-, 130-, 215-, and 400-fold less). In contrast, IGF-II mRNA was expressed at higher levels than in bone and liver (65- and 2-fold). IGF-II expression was higher in the proliferative and resting zones compared with the hypertrophic zone (P < 0.001). GH receptor and type 1 and 2 IGF receptors were expressed throughout the growth plate. Expression of IGF-binding proteins (IGFBPs)-1 through -6 mRNA was low throughout the growth plate compared with perichondrium and bone. With increasing age (3-, 6-, 9-, and 12-week castrated rats), IGF-I mRNA levels increased in the proliferative zone (PZ) but remained at least tenfold lower than levels in perichondrium and bone. IGF-II mRNA decreased dramatically in PZ (780-fold; P < 0.001) whereas, type 2 IGF receptor and IGFBP-1, IGFBP-2, IGFBP-3, and IGFBP-4 increased significantly with age in growth plate and/or surrounding perichondrium and bone. These data suggest that IGF-I protein in the growth plate is not produced primarily by the chondrocytes themselves. Instead, it derives from surrounding perichondrium and bone. In addition, the decrease in growth velocity that occurs with age may be caused, in part, by decreasing expression of IGF-II and increasing expression of type 2 IGF receptor and multiple IGFBPs.

Catch-up growth is associated with delayed senescence of the growth plate in rabbits

In mammals, release from growth-inhibiting conditions results in catch-up growth. To explain this phenomenon, we proposed the following model: 1) The normal senescent decline in growth plate function depends not on age per se, but on the cumulative number of replications that growth plate chondrocytes have undergone. 2) Conditions that suppress growth plate chondrocyte proliferation therefore slow senescence. 3) After transient growth inhibition, growth plates are thus less senescent and hence show a greater growth rate than expected for age, resulting in catch-up growth. To test this model, we administered dexamethasone to growing rabbits to suppress linear growth. After stopping dexamethasone, catch-up growth occurred. In distal femoral growth plates of untreated controls, we observed a senescent decline in the growth rate and in the heights of the proliferative zone, hypertrophic zone, and total growth plate. During the period of catch-up growth, in the animals previously treated with dexamethasone, the senescent decline in all these variables was delayed. Prior treatment with dexamethasone also delayed epiphyseal fusion. These findings support our model that linear catch-up growth is caused, at least in part, by a delay in growth plate senescence.

Increased final height in precocious puberty after long-term treatment with LHRH agonists: the National Institutes of Health experience

We report 98 children who have reached final adult height in a long-term trial of LHRH agonist treatment. These children were 5.3 +/- 2.1 yr old at the start of treatment and were treated with either deslorelin (4 microg/kg.d sc) or histrelin (4-10 microg/kg.d) for an average of 6.1 +/- 2.5 yr. Final height averaged 159.8 +/- 7.6 cm in the 80 girls, which was significantly greater than pretreatment predicted height (149.3 +/- 9.6 cm) but still significantly less than midparental height (MPH) (163.7 +/- 5.6). Final height averaged 171.1 +/- 8.7 cm in the 18 boys, which was significantly greater than pretreatment predicted height (156.1 +/- 14.2 cm) but still significantly less than MPH (178.3 +/- 5.2 cm). However, the average adult height of the 54 children who had less than a 2-yr delay in the onset of treatment was not significantly different from their MPH, and 21 children exceeded MPH. Final height SD score correlated positively with duration of treatment (P < 0.01), midparental height (P < 0.001), predicted height at the start of treatment (P < 0.001), and growth velocity during the last year of treatment (P < 0.001) and correlated inversely with delay in the onset of treatment (P < 0.001), age at the start of treatment (P < 0.001), bone age at the start of treatment (P < 0.001), bone age at the end of treatment (P < 0.001), breast stage at the start of treatment (P = 0.02), and bone age minus chronological age at the start of treatment (P = 0.001). We conclude that LHRH agonist treatment improves the final height for children with rapidly progressing precocious puberty treated before the age of 8 yr for girls or 9 yr for boys. Less delay in the onset of treatment, longer duration of treatment, and lower chronological and bone age at the onset of treatment all lead to greater final height. All children with onset of pubertal symptoms before age 8 in girls and age 9 in boys should be evaluated for possible treatment. Treatment is appropriate in children with rapidly progressing puberty, accelerated bone maturation, and compromise of adult height prediction, regardless of bone age or chronological age at time of evaluation. However, once treatment is considered appropriate, it should be initiated quickly, because longer delays lead to shorter final height. In addition, the longer the treatment is continued, the greater is the final height outcome.

Effects of estrogen on growth plate senescence and epiphyseal fusion

Estrogen is critical for epiphyseal fusion in both young men and women. In this study, we explored the cellular mechanisms by which estrogen causes this phenomenon. Juvenile ovariectomized female rabbits received either 70 microg/kg estradiol cypionate or vehicle i.m. once a week. Growth plates from the proximal tibia, distal tibia, and distal femur were analyzed after 2, 4, 6, or 8 weeks of treatment. In vehicle-treated animals, there was a gradual senescent decline in tibial growth rate, rate of chondrocyte proliferation, growth plate height, number of proliferative chondrocytes, number of hypertrophic chondrocytes, size of terminal hypertrophic chondrocytes, and column density. Estrogen treatment accelerated the senescent decline in all of these parameters. In senescent growth plates, epiphyseal fusion was observed to be an abrupt event in which all remaining chondrocytes were rapidly replaced by bone elements. Fusion occurred when the rate of chondrocyte proliferation approached zero. Estrogen caused this proliferative exhaustion and fusion to occur earlier. Our data suggest that (i) epiphyseal fusion is triggered when the proliferative potential of growth plate chondrocytes is exhausted; and (ii) estrogen does not induce growth plate ossification directly; instead, estrogen accelerates the programmed senescence of the growth plate, thus causing earlier proliferative exhaustion and consequently earlier fusion.

Nodular Leydig cell hyperplasia in a boy with familial male-limited precocious puberty

In boys with familial male-limited precocious puberty, an activating mutation of the luteinizing hormone receptor causes Leydig cell hyperplasia, resulting in excess testosterone production. There are no reports of Leydig cell masses in boys with familial male-limited precocious puberty. We describe a 10-year-old boy with familial male-limited precocious puberty who developed Leydig cell nodules.

Regulation of growth plate chondrogenesis by bone morphogenetic protein-2

Bone morphogenetic proteins (BMPs) regulate embryonic skeletal development. We hypothesized that BMP-2, which is expressed in the growth plate, also regulates growth plate chondrogenesis and longitudinal bone growth. To test this hypothesis, fetal rat metatarsal bones were cultured for 3 days in the presence of recombinant human BMP-2. The addition of BMP-2 caused a concentration-dependent acceleration of metatarsal longitudinal growth. As the rate of longitudinal bone growth depends primarily on the rate of growth plate chondrogenesis, we studied each of its three major components. BMP-2 stimulated chondrocyte proliferation in the epiphyseal zone of the growth plate, as assessed by [(3)H]thymidine incorporation. BMP-2 also caused an increase in chondrocyte hypertrophy, as assessed by quantitative histology and enzyme histochemistry. A stimulatory effect on cartilage matrix synthesis, assessed by (35)SO(4) incorporation into glycosaminoglycans, was produced only by the highest concentration of BMP-2. These BMP-2-mediated stimulatory effects were reversed by recombinant human Noggin, a glycoprotein that blocks BMP-2 action. In the absence of exogenous BMP-2, Noggin inhibited metatarsal longitudinal growth, chondrocyte proliferation, and chondrocyte hypertrophy, which suggests that endogenous BMPs stimulate longitudinal bone growth and chondrogenesis. We conclude that BMP-2 accelerates longitudinal bone growth by stimulating growth plate chondrocyte proliferation and chondrocyte hypertrophy.

Boys with precocious puberty due to hypothalamic hamartoma: reproductive axis after discontinuation of gonadotropin-releasing hormone analog therapy

Hypothalamic hamartoma is an important cause of precocious puberty in boys. Although the GnRH analogs are known to be effective therapy, there are few studies of the recovery of the pituitary-gonadal axis following long-term treatment. To this end, we studied 11 boys with HH after 8.8+/-3.2 yr (range, 4.0-12.6) of treatment with the GnRH agonist D-Trp6,Pro9,NEt-LHRH. The patients' levels of LH and FSH, testosterone, testis volume, and body mass index were compared with those of six normal boys in pubertal stage IV-V. We found that the patients' mean +/- SD peak GnRH-stimulated LH and FSH had returned to the normal range by 1 yr after stopping therapy. Whereas testosterone returned to normal levels by 1 yr, the patients' testis volume remained smaller than normal until 2 yr after therapy. Ultrasonography revealed diffuse, punctate, echogenic foci in the testicular parenchyma of two patients; these were first observed during GnRH agonist therapy and persisted unchanged after discontinuation of treatment. Neither of these two patients reported pain or testicular discomfort, no mass or irregularity was detected by manual examination in either patient at any time, and levels of beta-hCG and alpha1-fetoprotein were normal. By 4 yr after therapy, all patients had pubertal stage V pubic hair; their body mass index was not different from that of the normal boys at any time point. The dimensions of the patients' hamartomas did not change during or after therapy, and no patient reported new neurological symptoms or signs suggestive of an enlarging lesion at any time during or after discontinuation of treatment. Two families did report episodes of emotional lability and truancy as the patients reentered puberty after discontinuation of treatment.

Regulation of fetal rat bone growth by C-type natriuretic peptide and cGMP

C-type natriuretic peptide (CNP) and its high affinity receptor-B are expressed in fetal bones. Here we show that CNP accelerates longitudinal growth of fetal rat metatarsal bones in organ culture by several mechanisms. First, CNP stimulates chondrocyte proliferation in the proliferative zone as assessed by [3H]thymidine incorporation. Second, CNP stimulates cell hypertrophy as assessed by quantitative histology. Third, CNP stimulates cartilage matrix production as assessed by incorporation of 35SO4 into glycosaminoglycans. Natriuretic peptide receptor-B contains an intracellular guanylyl cyclase catalytic domain. We therefore hypothesized that cyclic GMP (cGMP) would reproduce the effects of CNP on fetal bones. Consistent with this hypothesis, we found that 8-Br-cGMP, like CNP, stimulates longitudinal growth and glycosaminoglycan synthesis. However, unlike CNP, cGMP inhibits proliferation of growth plate chondrocytes and has no effect on hypertrophy. We conclude that CNP stimulates longitudinal bone growth by increasing chondrocyte proliferation, chondrocyte hypertrophy, and cartilage matrix production. cGMP, a second messenger for CNP, reproduces some but not all of the effects of CNP, suggesting that other signal transduction mechanisms may also be involved.

Retinoic acid is a potent regulator of growth plate chondrogenesis

Vitamin A deficiency and excess both cause abnormalities in mammalian longitudinal bone growth. Because all-trans retinoic acid (RA) is synthesized from vitamin A, we hypothesized that RA regulates growth plate chondrogenesis. Consistent with this hypothesis, a single oral dose of RA reduced the height of the rat proximal tibial growth plate. To determine whether RA acts directly on growth plate, fetal rat metatarsal bones were cultured in the presence of RA. In this system, RA inhibited longitudinal bone growth by three mechanisms: 1) decreased chondrocyte proliferation, (assessed by 3H-thymidine incorporation), particularly in the proliferative zone of the growth plate; 2) decreased matrix synthesis (assessed by 35SO4 incorporation into glycosaminoglycans); and 3) decreased cell hypertrophy (determined histologically). The growth-inhibiting effects of RA were completely reversed by a retinoic acid receptor (RAR) antagonist. In the absence of exogenous RA, this antagonist accelerated bone growth, as did an RA-specific neutralizing antibody, suggesting that endogenous RA negatively regulates growth plate chondrogenesis. We conclude that RA, acting through RARs, negatively regulates longitudinal bone growth by inhibiting growth plate chondrocyte proliferation, chondrocyte hypertrophy, and matrix synthesis.

Six-year results of spironolactone and testolactone treatment of familial male-limited precocious puberty with addition of deslorelin after central puberty onset

Short term treatment with spironolactone, testolactone, and, after the onset of central puberty, deslorelin can normalize the rate of growth and bone maturation in boys with familial male-limited precocious puberty. To test the hypothesis that this treatment can achieve long term normalization of the growth and development of these children, we examined the growth rate, bone maturation rate (change in bone age/change in chronological age), and predicted adult height of 10 boys who were treated with spironolactone (5.7 mg/kg x day) and testolactone (40 mg/kg x day) for at least 6 yr. Deslorelin (4 microg/kg x day) treatment was initiated 2.6 +/- 1.3 yr after beginning spironolactone and testolactone treatment. The growth rate normalized within 1 yr of starting treatment and remained normal during the next 5 yr of treatment (P < 0.001). The rate of bone maturation normalized during the second year of treatment and remained normal thereafter (P < 0.001). Predicted height increased from 160.7 +/- 14.7 centimeters at baseline to 173.6 +/- 10.1 centimeters after 6 yr of treatment (P < 0.05 during the fourth through the sixth year of treatment compared to baseline). We conclude that long term treatment with spironolactone, testolactone, and, after central puberty, deslorelin normalizes the growth rate and bone maturation and improves the predicted height in boys with familial male-limited precocious puberty. The ultimate effect of this approach on adult height will require further study.

Gonadotrophin and prolactin secretory dynamics in girls with normal puberty, idiopathic precocious puberty and precocious puberty due to hypothalamic hamartoma

OBJECTIVE

This study was designed to test the hypothesis that hypothalamic hamartoma causes precocious puberty through a different neuroendocrine mechanism than that of normal puberty or of idiopathic precocious puberty.

DESIGN AND PATIENTS

We compared the pattern of gonadotrophin secretion among 4 girls with precocious puberty due to hypothalamic hamartoma, 27 girls with idiopathic precocious puberty, and 14 girls with normal puberty. All subjects were breast stage 3 or 4. Blood samples were obtained every 20 min for 4 h during the day (1.000 hours to 1400 h) and night (22.00 hours to 0200 h).

MEASUREMENTS

LH, FSH, and prolactin were measured in each blood sample. Girls also underwent LHRH-stimulation with measurement of LH and FSH before and after stimulation.

RESULTS

There were no significant differences in mean LH level, LH peak amplitude, or LH or FSH peak frequency during either the day or the night among the three diagnostic groups. However, the mean +/- SD LHRH-stimulated peak LH levels were greater in girls with hypothalamic hamartoma than in girls with normal puberty or with idiopathic precocious puberty (194 +/- 142 vs 85 +/- 60 or 66 +/- 54 IU/l, respectively, P < 0.05). The LHRH-stimulated peak FSH level in girls with hypothalamic hamartoma exceeded the level for the normal pubertal girls (31 +/- 19 vs 17 +/- 7 IU/l, P < 0.05), but not the level for the girls with idiopathic precocious puberty (25 + 12 IU/l). The peak LH to peak FSH ratio in the girls with hypothalamic hamartoma exceeded the ratio for the girls with idiopathic precocious puberty (7.3 +/- 3.9 vs 2.6 +/- 3.0 IU/l, P < 0.05), but not the ratio for the normal pubertal girls (5.0 + 2.9). There were no significant differences in mean prolactin level, peak amplitude or frequency, or in the ratio of mean night to mean day prolactin, among the 3 diagnostic groups.

CONCLUSIONS

We conclude that spontaneous gonadotrophin and prolactin secretion are similar among girls with hypothalamic hamartoma, idiopathic precocious puberty, or normal puberty. However, the increased LHRH-stimulated peak LH in the girls with hypothalamic hamartoma suggests subtle differences in neuroendocrine regulation that may underlie their more rapid pubertal maturation.

Use of an ultrasensitive recombinant cell bioassay to determine estrogen levels in girls with precocious puberty treated with a luteinizing hormone-releasing hormone agonist

Although treatment of girls with precocious puberty should ideally restore estradiol levels to the normal prepubertal range, treatment effectiveness has usually been monitored by gonadotropin levels because estradiol RIAs have lacked sufficient sensitivity to monitor treatment effectiveness. We hypothesized that a recently developed ultrasensitive recombinant cell bioassay for estradiol would have sufficient sensitivity to demonstrate a dose-dependent suppression of estradiol during LH-releasing hormone agonist treatment and to determine whether currently used doses are able to suppress estradiol levels to the normal prepubertal range. Twenty girls with central precocious puberty were assigned randomly to receive deslorelin for 9 months at a dose of 1, 2, or 4 micrograms/ kg.day. A significant dose-response relationship was observed, with mean +/- SD estradiol levels of 16.7 +/- 6.1, 7.9 +/- 1.6, and 6.5 +/- 0.7 pmol/L at the doses of 1, 2, and 4 micrograms/kg.day, respectively (P < 0.01). The highest dose suppressed estradiol levels to just above the 95% confidence limits for normal prepubertal girls (< 0.07-6.3 pmol/L). We conclude that the ultrasensitive bioassay for estradiol has sufficient sensitivity for monitoring the response to LH-releasing hormone agonist treatment of central precocious puberty. Additionally, the observation that the deslorelin dose of 4 micrograms/kg.day did not fully restore estradiol levels to the normal prepubertal range suggests that some girls with precocious puberty may require higher doses to receive the maximal benefit of treatment. We suggest that restoration of estradiol levels to the normal prepubertal range should be the ultimate biochemical measure of efficacy, as estradiol is the key hormone that accelerates growth rate, bone maturation rate, and breast development in girls with precocious puberty.

A preliminary study of flutamide, testolactone, and reduced hydrocortisone dose in the treatment of congenital adrenal hyperplasia

Treatment outcome in congenital adrenal hyperplasia is often suboptimal due to hyperandrogenism, treatment-induced hypercortisolism, or both. As a new approach, we hypothesized that the effects of androgen could be blocked by an antiandrogen (flutamide) and an inhibitor androgen to estrogen conversion (testolactone), thus allowing the hydrocortisone dose to be reduced. We conducted a short term pilot study in 12 children with congenital adrenal hyperplasia in a randomised cross-over open design to determine whether flutamide, testolactone, reduced hydrocortisone dose, and fludrocortisone are more effective than hydrocortisone and fludrocortisone treatment in normalizing linear growth, weight gain, and bone maturation. Each regimen was administered for 6 months, with a 3-month washout period, consisting of hydrocortisone and fludrocortisone treatment, between regimens. Compared to hydrocortisone and fludrocortisone treatment, the regimen of flutamide, testolactone, reduced hydrocortisone dose (from 12.9 to 7.9 mg/m2 day), and fludrocortisone produced an increase in plasma 17-hydroxyprogesterone levels (P < 0.05) and a decline in urinary cortisol (P < 0.01), linear growth rate (-0.9 +/- 0.5 vs. 1.4 +/- 0.6 SD U; P = 0.003), weight velocity (-0.80 +/- 4.0 vs 0.6 +/- 0.4 SD U; P = 0.01), and bone maturation (0.6 +/- 0.6 vs. 1.4 +/- 0.9 yr bone age/yr chronological age; P = 0.02). Although no important adverse effects were observed, the known potential for flutamide-induced hepatotoxicity made frequent monitoring essential. We conclude that the regimen of flutamide, testolactone, reduced hydrocortisone does, and fludrocortisone improve the short term control of growth and bone maturation in children with congenital adrenal hyperplasia. Long term studies are required to determine whether this approach can improve these children's growth and development.

Recovery of reproductive function in rats treated with the aromatase inhibitor fadrozole

The aromatase inhibitor, fadrozole hydrochloride (CGS 16949A), was developed for the treatment of breast cancer, and has not been available for pediatric use because of the lack of information about potential reproductive toxicology. To determine the effect of fadrozole on subsequent fertility and reproductive performance in rats, peripubertal male and female Sprague-Dawley rats (10/group) were given fadrozole by oral gavage once a day for 60 consecutive days (age 21 through 80 d) at a dose of 0, 1200, or 6000 micrograms/kg/d (dose range in women with breast cancer: 60 to 240 micrograms/kg/d). Following a 30-d recovery period (days 81 through 111 of age), cohabitation with untreated rats of the opposite sex was accomplished for 30 d or until positive evidence of mating was obtained (daily vaginal smears). The nonfadrozole-treated males used for cohabitation were proven fertile breeders; the females were virgin with proven 4-d estrous cycles. The duration of pregnancy, number, sex, condition, and body weight of pups were determined. Pregnant rats were weighed on gestational days 7, 14, and 20. There was a profound decrease in the number of estrous cycles at both dose levels of fadrozole compared to the control (P < 0.001). During the 30-d recovery period, estrous cycles were reestablished within a few days in the treated rats and the number and length of estrous cycles were not statistically different between fadrozole-treated and control rats. The gestational body weights of fadrozole-treated and untreated females did not differ significantly. There were no statistically significant differences in the number of matings/number of pairings, gestational length, mean live pups/litter, % pups born alive/litter, and % male pups/litter in the three groups (vehicle-, low-, and high-dose fadrozole-treated females, cohabited with untreated males and fadrozole-treated males, cohabited with untreated females). Thus, young male and female rats treated for 60 d with large doses of fadrozole had no detectable adverse effect on subsequent reproductive function.

Insulin-like growth factor I (IGF-I) and IGF-binding protein-3 concentrations compared to stimulated and night growth hormone in the evaluation of short children--a clinical research center study

To evaluate the relative usefulness of insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) in screening for GH status, GH stimulation (arginine-insulin/L-DOPA) tests and overnight GH studies (every 20 min sampling) were performed in 104 healthy short children (32 girls), aged 3-16 yr (height, -1.8 or more SD). IGFBP-3 had no advantage over IGF-I in screening sensitivity or specificity. IGF-I correlated with mean nighttime GH. Both IGF-I and IGFBP-3 correlated with peak stimulated GH. To identify more than 90% of children with GH deficiency (GHD) and borderline GHD, the mean values for age for IGF-I and IGFBP-3 were required as the cut-off criterion. However, at this criterion, 70% or more of idiopathic short stature (ISS) children would have to undergo testing to identify 90% of GHD or borderline GHD. More stringent criteria (-1.0, -1.64, and -2.0 SD) were more specific, but lost sensitivity. A practical application is suggested. Screening use of IGF-I with criterion of -1.0 SD would identify a subgroup that includes 88% of GHD, 71% of borderline GHD, and 46% of ISS. Both IGF-I and IGF-BP-3 higher than -1.0 SD would accurately identify 68% of ISS as not needing GH testing. Evaluation of growth velocity would identify the remaining children requiring definitive testing. Thus, combined screening for GHD using both IGF-I and IGFBP-3 has no better sensitivity than either test alone. However, such combined screening will improve the specificity and thus decrease the number of normal but short children who might otherwise undergo unnecessary testing.

Steroid treatment, accumulation, and antagonism of P-glycoprotein in multidrug-resistant cells

According to multiple reports, progesterone is not transported by P-glycoprotein (Pgp), which mediates multidrug resistance through active drug efflux. However, progesterone has been shown to block Pgp- mediated efflux of other drugs. To extend these observations and to examine the effect of modulating Pgp phosphorylation, the accumulation of progesterone and 14 other steroids in untreated and calphostin C-treated multidrug-resistant human colon carcinoma SW620 Ad300 cells was compared to the accumulation in parental SW620 cells. However, the accumlation of more hydrophilic steroids was reduced by as much as 50%. Progesterone and progesterone-like compounds, however were potent inhibitors of Pgp-mediated vinblastine efflux; increased antagonism correlated with increased steroid hydrophobicity. Treatment with calphostin C, a PKC inhibitor which decreases Pgp phosphorylation, increased progesterone efflux, modulated Pgp antagonism by steroids, and inhibited photoaffinity labeling of Pgp by progesterone. These results extend previous observations that Pgp can mediate the transport of, and be antagonized by, a variety of steroids and that these properties vary with both steroid's hydrophobicity and the phosphorylated state of Pgp.

Overnight growth hormone concentrations are usually normal in pubertal children with idiopathic short stature--a Clinical Research Center study

To estimate the incidence of low growth hormone (GH) concentration in children and adolescents with idiopathic short stature, overnight GH levels were measured in 167 subjects. The results were compared with data from 132 normal children of similar pubertal stage, bone age, or body mass index. The majority of short children had normal overnight GH concentrations in a distribution not significantly different from that observed in normal children. However, in 6% of children grouped by pubertal stage and in 13% of children grouped by bone age, overnight GH levels were below the 95% confidence limits of normal. The overnight GH levels were above normal in 6%. The observed frequencies of both low and high GH levels were significantly greater than expected (P < 0.001). However, when body mass index was included in the analysis, only 5% of the children had low GH measures, and only 4% had high GH measures (both not significant). This frequency of low overnight GH levels in short children is considerably less than that reported by others. Thus, these data do not support the hypothesis that a deficiency of spontaneous GH secretion is a common cause of short stature. We conclude that standard GH stimulation tests, despite their limitations, remain the best definitive test of GH secretion. Subsequent overnight GH studies may be useful, however, in selected clinical settings such as previous cranial irradiation or other central nervous system disorder.

Thyroid function in non-growth hormone-deficient short children during a placebo-controlled double blind trial of recombinant growth hormone therapy

GH treatment in GH-deficient children has been reported to cause decreases in serum T4 and TSH and an increase in serum T3. We sought to determine whether GH treatment alters thyroid function in non-GH-deficient short children. Twenty children (18 boys) were followed for 12 months while receiving either GH (Humatrope, Eli Lilly; 0.074 mg/kg, sc, 3 times/week; n = 9) or placebo (n = 11). Total T4, free T4, T3, and TSH were measured every 6 months and in 12 children also at 1, 2, 3, and 9 months. A TRH test and measurement of nocturnal TSH surge were performed at baseline and after 6 months of treatment in 19 subjects. There were no significant differences at baseline in the clinical features between the placebo and GH groups. Total T4, free T4, T3, and TSH levels did not significantly differ between the placebo and GH groups at baseline and at 1, 2, 3, 6, 9, and 12 months. There were no significant differences between the two groups in TSH response to TRH or nocturnal TSH surge. Although an early transient effect of GH treatment could not be excluded, we conclude that GH treatment for 12 months does not produce sustained alterations in thyroid function in non-GH-deficient children.

The effects of estrogen priming and puberty on the growth hormone response to standardized treadmill exercise and arginine-insulin in normal girls and boys

To determine the effects of puberty and estrogen priming on the GH response to standardized treadmill exercise and arginine-insulin in normal boys and girls, we performed tests in 84 normal children (41 girls and 43 boys) representing all stages of puberty. A subset of the prepubertal children received the tests twice, with or without the administration of ethinyl estradiol (40 micrograms/m2 daily) for 2 days before the tests. The peak GH response to the three tests increased significantly with pubertal stage (r = 0.57; P < 0.0001), but did not differ between boys and girls at the same stage. With advancing puberty, the percentage of normal children who failed to attain a GH level greater than 7 micrograms/L during any of the three tests declined from 61% at pubertal stage 1 to 44% at stage 2, 11% at stage 3, and 0% at stages 4 and 5. Administration of estrogen to the prepubertal subjects raised the normal range for the peak GH response to the three tests from 1.9-20.3 to 7.2-40.5 micrograms/L. We conclude that both puberty and estrogen administration significantly increase the peak GH response to exercise, arginine, or insulin in normal subjects. Moreover, the conventional criterion that the peak GH response to three stimulation tests should exceed 7 micrograms/L was applicable in our study only to subjects who had attained pubertal stage 4 or 5 or who had received estrogen administration.

Effect of deslorelin-induced pubertal delay on the growth of adolescents with short stature and normally timed puberty: preliminary results

LH-releasing hormone agonist (LHRHa) treatment slows bone maturation and improves adult height in children with LHRH-dependent precocious puberty. To determine whether pubertal delay induced by LHRHa can enhance final height in patients with short stature and a normally timed puberty, we enrolled 43 short children (28 girls and 15 boys) in a double blind, placebo-controlled trial. Patients were assigned randomly to receive either placebo or LHRHa (deslorelin), administered sc at a dose of 4 micrograms/kg.day for a period of 4 yr. This report describes the preliminary results in 16 children who have completed 4 yr of treatment (9 patients in the deslorelin group and 7 patients in the placebo group). Predicted adult height increased significantly in the deslorelin-treated patients, by 7.6 cm compared to the pretreatment baseline and by 10.3 cm compared to that in the placebo-treated patients (P < 0.005). Four of the 16 patients received concurrent GH treatment (3 among the deslorelin-treated patients and 1 among the placebo-treated patients). Omitting these patients from the analysis did not materially affect the results: predicted adult height in the deslorelin-treated patients increased by 7.2 cm compared to the pretreatment baseline and by 10.9 cm compared to that in the placebo-treated patients (P < 0.005). We conclude that pubertal delay induced by deslorelin significantly increases predicted adult height in adolescents with short stature and a normally timed puberty. Whether deslorelin treatment will increase the final height of these patients cannot be determined until they have stopped growing.

Treatment of familial male precocious puberty with spironolactone, testolactone, and deslorelin

Combined antiandrogen (spironolactone) and aromatase inhibitor (testolactone) are effective for the short term treatment of familial male precocious puberty. During this therapy, plasma testosterone levels remain in the adult range, since spironolactone blocks the testosterone receptor without significantly affecting plasma testosterone levels. After our initial 18-month pilot study, we continued to treat eight boys with the combined therapy for 2.0-4.2 yr. During this time all boys exhibited a pubertal rise in gonadotropin secretion and a diminishing response to treatment, which was manifested by the recurrence of clinical features of puberty and an increase in the bone maturation rate (P < 0.05). Addition of the LHRH agonist deslorelin (4 micrograms/kg.day, sc) to the combined therapy decreased peak LH, plasma testosterone, bone maturation rate, and growth velocity (P < 0.05) over the next year. We conclude that the rise in gonadotropin levels during central activation of hypothalamic LHRH secretion in boys with familial male precocious puberty causes a partial escape from the combined effect of spironolactone and testolactone. The addition of deslorelin to the combined therapy appears to restore the control of puberty in this setting.

The effect of pubertal delay on adult height in men with isolated hypogonadotropic hypogonadism

To determine whether delay of puberty alters adult height, we retrospectively evaluated the adult height of 41 patients who met rigorous criteria for the diagnosis of isolated hypogonadotropic hypogonadism. The adult height of these patients was compared with the mean height of normal American men at age 18 in the 1979 National Center for Health Statistics survey and with the mean adult height of 50 male normal volunteers who had been studied on the same wards as the patients with hypogonadotropic hypogonadism. The mean adult height of the men with isolated hypogonadotropic hypogonadism was 179.7 cm, which exceeded the height of the 50 control subjects and the normal American men (both 176.8 cm) by 2.9 cm (P less than 0.05 and P less than 0.006, respectively). The mean age at treatment to induce puberty was 20.0 yr, which corresponded to a mean delay in the onset of puberty of more than 8 yr relative to normal males. The final height of the men with hypogonadotropic hypogonadism correlated significantly with the duration of pubertal delay (r = 0.32, P = 0.04). Most of the enhanced mean adult height of the patients with isolated hypogonadotropic hypogonadism was attributable to those patients in whom treatment to induce puberty had been delayed to age 18 or greater. The mean adult height of these patients was 182.4 cm, or 5.6 cm greater than the mean height of the 50 controls or of normal American men (P less than 0.001). The mean adult height of patients whose treatment began between 10 and 17 yr of age was 175.0 cm, which did not differ significantly from that of normal men. We conclude that prolonged delay of puberty (6 or more yr) in men with isolated hypogonadotropic hypogonadism is associated with a modest increase (approximately 5 cm) of adult height.

Adult height in precocious puberty after long-term treatment with deslorelin

Precocious puberty often leads to short adult height. Since the introduction of luteinizing hormone-releasing hormone (LHRH) agonist treatment for LHRH-dependent precocious hormone (LHRH) agonist treatment for LHRH-dependent precocious puberty in 1979, several reports have shown increased predicted height among LHRH agonist-treated children. To determine whether the LHRH agonist deslorelin can normalize the adult height of children with precocious puberty, we are conducting a long-term pilot study involving 161 children. This report describes the first 44 children to have attained final or proximate adult height. These children were 7.1 +/- 1.2 (mean +/- SD) yr old (bone age 11.8 +/- 1.5 yr) and had been in puberty for 3.1 +/- 0.3 yr at the start of treatment. They were treated with deslorelin (4 micrograms/kg/day sc) for 4.1 +/- 1.3 yr and had been withdrawn from treatment for an average of 2.4 yr at the time of this study (age 13.6 +/- 0.9 yr). Fourteen of the 44 children, who had grown less than 0.5 cm during the previous year, were considered to have attained adult height. The other 30 children had achieved 98.6% of predicted mature height (Bayley-Pinneau method) and were considered to be at proximate adult height. The final or proximate adult height of these 44 children averaged -1.1 SD compared to the adult height of the normal population. This height was significantly greater than the pretreatment height (-1.1 vs. -2.0 SD, P less than 0.01), but significantly less than both the predicted height at the end of treatment (-1.1 vs. -0.5 SD, P less than 0.01) and the target height derived from the mean height of the parents adjusted for the sex of the child (-1.1 vs. 0.1 SD, P less than 0.01). The observation that the Bayley-Pinneau height prediction at the end of treatment overestimated the actual adult height emphasizes the importance of using final height data to assess the ultimate impact of LHRH agonist treatment. It also indicates the need for caution when predicting the adult height of children who are still receiving treatment. We conclude that deslorelin has improved the adult height of these patients but has not fully restored height to the patients' genetic potential. We hypothesize that further improvement will be seen in patients who are treated with less delay and at a younger bone age.

Spontaneous growth hormone secretion increases during puberty in normal girls and boys

To test the hypothesis that GH secretion increases during puberty, we measured GH levels in samples obtained every 20 min for 24 h from 132 normal children and adolescents. In both girls and boys, GH levels increased during puberty. The increase in mean levels was earlier in girls than boys, was most evident at night, and was due to increased pulse amplitude rather than a change in pulse frequency. The mean nighttime GH level in girls with bone ages (BA) greater than 12 to 14 yr were significantly greater than the mean level in girls with BA less than 8 yr (7.3 +/- 3.0 vs. 3.4 +/- 1.7 micrograms/L; P less than 0.01) and were greatest at breast stage 3 (7.9 +/- 2.5 micrograms/L). GH pulse amplitude increased significantly before pubertal onset in girls and was significantly greater at BA greater than 12 to 14 yr than at BA of 8 yr or less (13.9 +/- 6.0 vs. 7.9 +/- 4.8 micrograms/L; P less than 0.01) and greatest at breast stage 3 (15.0 +/- 6.3 micrograms/L). The pubertal increase in GH secretion was delayed in boys compared to girls, with the lowest mean 24-h GH and mean nighttime GH values in boys with BA greater than 8 to 11 yr. The mean nighttime GH level at BA greater than 11 to 13 yr in boys was significantly greater than that in the boys with BA greater than 8 to 11 yr (5.8 +/- 2.9 vs. 3.5 +/- 2.1 micrograms/L; P less than 0.05) and was greatest at a testicular volume of more than 10 to 15 mL (6.5 +/- 2.0 micrograms/L). The mean nighttime GH pulse amplitude in boys was significantly greater at BA greater than 11 to 13 yr than at BA greater than 8 to 11 yr (13.9 +/- 5.7vs. 7.3 + 2.6 micrograms/L, P less than 0.05) and was greatest at a testicular volume greater than 20 mL (15.8 +/- 12.0 micrograms/L). The mean nighttime GH levels correlated inversely with body mass index in both sexes, although the correlation achieved statistical significance only for the girls, being stronger in breast stage 3 to 5 girls (r = -0.57 P = 0.0007; n = 32) than in stage 1 and 2 girls (r = -0.38; P = 0.03; n = 32). These observations in normal adolescents emphasize the importance of interpreting spontaneous GH levels in short children in relation to normative data appropriate for sex, body mass, and bone age or pubertal stage.

Low growth hormone levels are related to increased body mass index and do not reflect impaired growth in luteinizing hormone-releasing hormone agonist-treated children with precocious puberty

To test the hypothesis that GH deficiency might explain the low growth velocity of some LHRH agonist (LHRHa)-treated children with central precocious puberty, we measured stimulated (n = 81) and spontaneous (n = 32) GH levels during or after LHRHa treatment. GH stimulation tests in the children who were receiving LHRHa treatment were performed after 2 days of ethinyl estradiol administration. Thirty-one of 81 children (38%) who underwent GH stimulation tests had subnormal responses (less than or equal to 7 micrograms/L) to all tests administered (at least 2 stimuli), including 22 of 67 (33%) who had precocious puberty that was idiopathic or associated with hypothalamic hamartoma. Eleven of 32 children (34%) who underwent measurement of the mean nighttime spontaneous GH level had levels below the normal range for prepubertal children (less than 1.2 microgram/L). Despite the high incidence of subnormal GH levels, there appeared to be no relationship between the GH levels of these children and their growth characteristics. The height, growth velocity, bone maturation rate, predicted height, and insulin-like growth factor-I levels were not different between the children with low GH levels and the children with normal GH levels. Conversely, the GH levels were not different between the children with subnormal growth rates and the children with normal growth rates. Thus, variation in the growth rates of these LHRHa-treated children with central precocious puberty could not be explained by variation in the stimulated or spontaneous secretion of GH. In attempting to understand the high incidence of low GH levels in children with precocious puberty, we examined the relationship between GH level and body mass index (BMI). Both the stimulated (r = -0.33; P less than 0.002) and the spontaneous (r = -0.61; P less than 0.0002) GH levels were inversely related to BMI. Moreover, the children with precocious puberty as a group had significantly elevated BMI [1.2 +/- 0.1 (+/- SE) SD units] compared to normal children of the same age (P less than 0.0001). Thus, increased body mass may explain the high incidence of subnormal GH levels in these patients, and normative GH levels adjusted for body mass are needed before it can be concluded that the apparently subnormal GH levels in LHRHa-treated children with precocious puberty are in fact low.

A novel testis-stimulating factor in familial male precocious puberty

BACKGROUND

Familial male precocious puberty is a gonadotropin-independent form of precocious puberty that occurs only in males. The cause of the disorder is unknown. To examine the hypothesis that the plasma of boys with familial male precocious puberty contains a novel stimulator of testicular testosterone production, we developed a bioassay using adult male cynomolgus monkeys.

METHODS

We collected plasma from 12 boys with familial male precocious puberty, 7 normal prepubertal boys of similar ages and with similar plasma gonadotropin levels, and 1 boy with hypogonadotropic hypogonadism and infused it into the testicular artery of adult male cynomolgus monkeys that had been pretreated with gonadotropin-releasing-hormone antagonist to inhibit the endogenous secretion of gonadotropins. Testicular venous effluent was collected at 15-minute intervals for 3 or 5 hours for the measurement of testosterone.

RESULTS

The mean (+/- SE) peak testosterone response, as compared with base line, was significantly greater in the monkeys infused with plasma from the 12 boys with familial male precocious puberty than in the monkeys infused with plasma from the 7 normal prepubertal boys and the boy with hypogonadotropic hypogonadism (385 +/- 51 vs. 184 +/- 25 percent, P less than 0.005) in the three-hour studies. Plasma from 92 percent of the boys with familial male precocious puberty and 12.5 percent of the normal prepubertal boys stimulated a response greater than 195 percent of base-line values. In the animals studied for five hours after receiving a second dose of antagonist, the mean peak testosterone response, as compared with base line, was significantly greater in the monkeys infused with plasma from three boys with familial male precocious puberty than in the monkeys infused with plasma from three normal prepubertal boys (363 +/- 81 vs. 115 +/- 6 percent, P less than 0.01). The mean area under the testosterone-response curve was significantly larger in the monkeys infused with plasma from the boys with familial male precocious puberty in the five-hour studies (154 +/- 34 vs. -58 +/- 10 percent, P less than 0.005), but not in the three-hour studies.

CONCLUSIONS

These findings support the presence of a circulating testis-stimulating factor in the plasma of boys with familial male precocious puberty. The production of such a factor would explain the biologic nature of the disorder.

Effect of deslorelin dose in the treatment of central precocious puberty

Central precocious puberty is effectively treated with long-acting LHRH analogs (LHRHas). Although at least six LHRHas have now been used in children, there have been no studies to determine the least effective dose of any of these analogs. We sought to determine the effect of decreasing an efficacious dose of deslorelin (D-Trp6-Pro9-NEt-LHRH) on basal and LHRH-stimulated gonadotropins, estradiol levels, and the rates of linear growth and skeletal maturation in subjects with central precocious puberty. Twenty-nine children with central precocious puberty were enrolled in a double blinded study. All subjects were treated for the initial 3 months with deslorelin at a dose (4 micrograms/kg.day, sc) known to suppress gonadotropins, linear growth velocity, and the rate of skeletal maturation. After 3 months, the subjects were randomly assigned to receive one of three daily sc doses of deslorelin: 4 micrograms/kg (n = 9), 2 micrograms/kg (n = 11), or 1 micrograms/kg (n = 9). They were treated at this dose in double blinded fashion for 15 months, after which time they resumed therapy at a dose of 4 micrograms/kg.day for an additional year. The children in the three groups did not differ in terms of chronological age, bone age, pretreatment growth rate, or Tanner stage at the onset of therapy. Similarly, there were no differences in the clinical and hormonal responses to the first 3 months of LHRHa therapy (4 micrograms/kg.day). During the 15-month period at the three different doses, the three dose groups could not be distinguished from each other in terms of pubertal stage, linear growth velocity, rate of skeletal maturation, sex steroid levels, mean LH or FSH levels, or peak FSH response to LHRH stimulation or to a dose of deslorelin. In contrast, the peak LH response to LHRH stimulation was highest in children treated with the lowest dose (1 micrograms/kg.day; P less than 0.025, by multiple analysis of variance). In addition, the peak LH response to a dose of deslorelin (the LHRHa test) was higher in children treated with 1 micrograms/kg.day than in those treated with 4 micrograms/kg.day (P less than 0.04). In summary, the LHRHa test is a sensitive means for detecting activation of the hypothalamic-pituitary-gonadal axis, and deslorelin at a dose of 1 micrograms/kg.day results in less gonadotropin suppression than a dose of 4 micrograms/kg.day.(ABSTRACT TRUNCATED AT 250 WORDS)

Gonadotropin secretory dynamics during puberty in normal girls and boys

To determine the most useful index of pubertal gonadotropin secretion we measured spontaneous LH and FSH levels every 20 min for 24 h and the LH and FSH responses to LHRH in a total of 37 girls and 30 boys representing each of the 5 stages of puberty. Mean 24-h LH and FSH levels rose significantly with increasing pubertal stage in both girls and boys. LH peak amplitude increased significantly with increasing pubertal stage for both sexes, whereas FSH peak amplitude did not. LH and FSH peaks were present throughout the 24-h period in all children, but the frequency did not change significantly with increasing pubertal stage. Mean gonadotropin levels, peak amplitudes, and peak frequencies tended to be higher at night from pubertal stages 1-4 of puberty. There were no significant sex differences in mean LH, LH peak amplitude, or LH peak frequency. The LHRH-stimulated peak LH to peak FSH ratio was greater in boys than girls during pubertal stages 1-3 and was less useful in distinguishing pubertal from prepubertal boys. For girls, the most accurate index of pubertal gonadotropin secretion was a LHRH-stimulated peak LH to peak FSH ratio greater than 0.66, which detected 96% of the pubertal girls with no false positives. For boys, the most accurate index was a maximum spontaneous nighttime LH level of 12 IU/L or more, which detected 90% of the pubertal boys with no false positives. We conclude that there are important sex differences in the gonadotropin responses to LHRH during puberty, and that criteria for the onset of pubertal gonadotropin secretion should be sex specific.

Effect of thyroid hormone on epidermal growth factor-like immunoreactivity and growth velocity in cynomolgus monkeys

To examine the potential role of epidermal growth factor (EGF) in mediating the effects of thyroid hormone on linear growth, we measured serum EGF levels by RIA in cynomolgus monkeys before and during methimazole-induced hypothyroidism, and after 9 weeks of T4 replacement at different doses. Ten castrated prepubertal monkeys were rendered hypothyroid by methimazole (0.0125% in drinking water for 12 weeks). Methimazole was continued, and T4 was then administered for 9-week intervals. Six weeks elapsed between successive T4 doses. The sequence of different T4 doses for each animal was random. Serum EGF level was measured at baseline and at the end of each treatment period with a newly developed RIA using a polyclonal antiserum against human recombinant EGF. Serum EGF level correlated significantly with the level of serum thyroxine but not with serum triiodothyronine, over the thyroxine dosage range of 1-4 micrograms/kg/day (r = 0.41, p less than 0.005). Lower-leg growth rate correlated significantly with serum EGF level over this same thyroxine dosage range (r = 0.41, p less than 0.005). These data are consistent with the hypothesis that EGF may mediate some of the effects of thyroid hormone on skeletal growth.

The effect of pulsatile human corticotropin-releasing hormone administration on the adrenal insufficiency that follows cure of Cushing's disease

Successful transsphenoidal surgery for Cushing's disease leads to secondary adrenal insufficiency in most patients. This form of transient adrenal insufficiency is thought to result from hypothalamic and pituitary suppression due to the preceding hypercortisolism. Whether the rate-limiting step in the recovery of adrenal function in this setting is the hypothalamic CRH neuron or the pituitary corticotroph cell, however, is not known. We studied this question by examining the response to ovine CRH (oCRH) before, during, and after prolonged pulsatile administration of human CRH (hCRH) beginning 1-2 weeks after curative microadenomectomy for Cushing's disease. Five patients cured of Cushing's disease received eight hCRH injections (1 microgram/kg) daily for 7 days. This CRH regimen was found previously to normalize plasma ACTH and cortisol patterns in patients with secondary adrenal insufficiency who had normal ACTH responses to a single injection of oCRH (hypothalamic adrenal insufficiency). The plasma ACTH and cortisol responses to oCRH (1 microgram/kg at 2000 h) were assessed immediately before, 2.5 h after, and 7 days after the end of pulsatile hCRH administration. To control for time-related improvement in the hormonal response to ovine CRH, an additional five patients cured of Cushing's disease underwent oCRH tests 1-2 and 3-4 weeks after transsphenoidal surgery, but did not receive hCRH. There was no significant difference in basal or oCRH-stimulated plasma ACTH and cortisol levels among any of the three oCRH tests in the patients who received hCRH. The baseline and oCRH-stimulated plasma ACTH and cortisol levels 1-2 and 3-4 weeks after surgery in the patients who did not receive pulsatile hCRH were similar to the values at those times in the patients who received pulsatile hCRH. Compared to normal subjects, however, both the hCRH-treated and non-hCRH-treated patients had significantly decreased peak and time-integrated plasma ACTH and cortisol responses to oCRH. We conclude that an impaired pituitary response to CRH contributes to the postoperative hypocortisolism of patients recently cured of Cushing's disease, and that this impaired pituitary response to CRH is not reversible by 1 week of pulsatile hCRH administration.

Treatment of familial male precocious puberty with spironolactone and testolactone

Because the pubertal growth spurt in boys appears to be mediated by both androgens and estrogens, we hypothesized that blockade of both androgen action and estrogen synthesis would normalize the growth of boys with familial male precocious puberty. To test this hypothesis, we studied nine boys (age range, 3.3 to 7.7 years) during treatment with an antiandrogen (spironolactone) or an inhibitor of androgen-to-estrogen conversion (testolactone), followed by treatment with both agents. After six months of observation without treatment, the first four boys received spironolactone for six months, followed by spironolactone and testolactone. The next five boys received testolactone for six months, followed by spironolactone and testolactone. Neither spironolactone nor testolactone, given alone, was satisfactory as a treatment for this condition. However, a combination of spironolactone and testolactone, given for at least six months, restored both the growth rate and the rate of bone maturation to normal prepubertal levels and controlled acne, spontaneous erections, and aggressive behavior. The combined therapy was associated with a significantly lower growth rate than testolactone alone (P less than 0.05) and a significantly lower rate of bone maturation than spironolactone alone (P less than 0.05). No important adverse effects were observed during combined treatment. Six of the nine boys continued to receive the combined therapy for an additional 12 months and maintained normal prepubertal rates of growth and bone maturation. The mean predicted height (+/- SEM) increased progressively during the combined treatment although the difference between the pretreatment and post-treatment predictions was not significant (169.5 +/- 2.8 at the end of treatment vs. 166.2 +/- 4.5 cm before treatment; P = 0.29). We conclude that blockade of both androgen action and estrogen synthesis with the combination of spironolactone and testolactone is an effective short-term treatment for familial male precocious puberty. Further study will be required, however, to assess the long-term outcome in boys who receive this treatment.

Two-year comparison of testicular responses to pulsatile gonadotropin-releasing hormone and exogenous gonadotropins from the inception of therapy in men with isolated hypogonadotropic hypogonadism

Men with the complete form of isolated hypogonadotropic hypogonadism (initial mean testes volume less than 4 mL) require 2 or more yr of exogenous gonadotropin therapy combining hCG and human menopausal gonadotropin (hMG) to achieve maximal, but subnormal, testis size and sperm output. To test whether pulsatile GnRH therapy, which more closely mimics normal hormonal stimulation, would accelerate or further augment testicular growth, hasten the onset of sperm production, and/or increase sperm output more than occurs during conventional exogenous gonadotropin therapy, we administered either hCG/hMG or GnRH from the inception of therapy to 2 comparable groups of men with complete IHH (initial testicular volume, less than 4 mL) and compared their testicular responses during the first 2 hr of therapy. Five men were treated with pulsatile GnRH in doses of 143-714 ng/kg every 2 h, sc, while 11 other men received hCG (2000 IU) and hMG (75 IU FSH and 75 IU LH) im 3 times/week. In the GnRH-treated men, the mean plasma total and free testosterone levels during therapy rose to within the normal range, but were significantly lower (P less than 0.01 and P less than 0.02, respectively) than those in the hCG/hMG-treated men. The mean plasma estradiol concentrations during therapy were within the high normal range and were similar in the two groups. The mean plasma FSH levels achieved in the GnRH-treated men were significantly (P less than 0.01) and 1.3- to 3.2-fold higher than those in the hCG/hMG-treated men. The mean testicular size achieved in the GnRH-treated men was not significantly different from that in the hCG/hMG-treated men (P = 0.08); the mean testicular volumes after 2 yr were 4.8- and 4.3-fold the pretreatment values in the GnRH and hCG/hMG groups, respectively. After 12 months of therapy, sperm production had occurred in one man in the GnRH group and in no subject in the hCG/hMG group. After 24 months, two men in the GnRH group and eight men in the hCG/hMG group produced sperm. Thus, 40% of the GnRH-treated men and 80% of the hCG/hMG-treated men (P = NS) produced sperm after 2 yr of therapy. The sperm concentrations in all men were below 5 million/mL and were comparable in the two groups (P = NS). These results suggest that pulsatile sc GnRH therapy for the first 2 yr does not accelerate or enhance testicular growth, hasten the onset of sperm production, or increase sperm output significantly compared to hCG/hMG.

Premature thelarche and central precocious puberty: the relationship between clinical presentation and the gonadotropin response to luteinizing hormone-releasing hormone

Premature thelarche is a benign condition that affects young girls. In contrast, central precocious puberty is considered a more serious disorder that causes progressive secondary sexual development, accelerated growth and skeletal maturation, early epiphyseal fusion, and short adult stature. Differentiation between these 2 conditions is important, but may be difficult on clinical grounds, since patients with both disorders may present initially as isolated breast development. To examine the potential usefulness of gonadotropin measurements in distinguishing early central precocious puberty from premature thelarche, we measured basal and LHRH-stimulated plasma gonadotropin levels in 58 girls with idiopathic premature breast development. The girls were divided into six clinically distinct groups, based on the severity of clinical presentation, ranging from isolated breast development (group A) to complete secondary sexual development and accelerated growth and skeletal maturation (group F). The mean basal plasma LH levels and the peak LH response to LHRH stimulation were significantly less in girls with isolated thelarche (group A) than in girls with complete sexual development (group F). The mean basal plasma FSH levels did not differ between these groups, but the peak FSH response to LHRH was greater in girls with isolated thelarche than in girls with complete sexual development. Thus, girls with isolated premature thelarche had a FSH-predominant response to LHRH [mean ratio of peak LH to peak FSH, 0.29 +/- 0.10 (+/- SD)], while girls with complete sexual development had a LH-predominant response (peak LH/FSH, 4.16 +/- 1.80). All girls with isolated thelarche had peak LH/FSH ratios less than 1, and all girls with complete sexual development had a ratio greater than 1. Girls with early or intermediate manifestations of central precocious puberty, who had features of puberty in addition to breast development but lacked all of the features of group F, comprised groups B-E. These girls also had intermediate peak LH/FSH ratios, ranging from 0.29 +/- 0.10 (group B) to 3.35 +/- 2.66 (group E). We conclude that girls with early central precocious puberty frequently have LH and FSH responses to LHRH that are indistinguishable from the FSH-predominant responses of girls with isolated thelarche. These data are consistent with the hypothesis that premature thelarche and central precocious puberty may represent different positions along a continuum of hypothalamic LHRH neuron activation.

Resumption of puberty after long term luteinizing hormone-releasing hormone agonist treatment of central precocious puberty

To determine whether puberty resumes normally after long term LHRH agonist (LHRHa) treatment, we studied 16 children with central precocious puberty treated with LHRHa (D-Trp6,Pro9,NEt-LHRH) for 1-4 yr (mean, 3.3 yr). Treatment was discontinued at a mean age of 11.6 +/- 1.3 (+/- SD) yr. Plasma hormone levels, growth velocity, rate of bone maturation, and pubertal stage were assessed at the end of treatment and 3 and 12 months later. Basal plasma sex steroid and basal and LHRH-stimulated gonadotropin levels returned to near-pretreatment levels 3 months after discontinuation of therapy and were fully restored to pretreatment levels at 12 months. Growth velocity, which had been 7.8 cm/yr before treatment, was stable after discontinuation of treatment at approximately 2.6 cm/yr. The predicted height, which had increased during treatment (P less than 0.01), remained stable at approximately 5 cm above the pretreatment predicted height. The rate of bone age advancement (delta bone age/delta chronological age) increased gradually from 0.4 at the end of treatment to the normal value of 0.9 12 months posttreatment. Breast and pubic hair pubertal stages, which were stable throughout treatment and were 4.0 +/- 0.8 (+/- SD) and 3.6 +/- 1.0 at the end of treatment, increased to 4.9 +/- 0.2 and 4.5 +/- 1.0. This approximated the normal rate of 1 stage/yr. Menses occurred in 8 of 12 girls within 1 yr after treatment and in an additional 3 by 20 months after treatment. Six of the girls had menstruated before treatment, and all of these menstruated within 14 months after discontinuing therapy. We conclude that gonadotropin and sex steroid secretion and the clinical progression through puberty appear to resume normally after discontinuation of long term LHRHa treatment of central precocious puberty. Long term follow-up will be required, however, to determine whether the improvement in predicted height of these patients will be achieved, and whether adult reproductive function will be normal.

The advantage of measuring stimulated as compared with spontaneous growth hormone levels in the diagnosis of growth hormone deficiency

To clarify the relative usefulness of measuring stimulated as compared with spontaneous growth hormone levels in the diagnosis of growth hormone deficiency, we studied 54 short prepubertal children--23 with growth hormone deficiency identified by stimulation tests and 31 with idiopathic short stature who had normal responses to growth hormone stimulation. Growth hormone levels were measured in plasma samples obtained every 20 minutes for either 12 or 24 hours. The results were compared with those in 46 normal prepubertal children. Children with growth hormone deficiency had significantly lower mean 24-hour growth hormone levels (1.0 microgram per liter; range, 0.5 to 1.8) than normal children (2.8 micrograms per liter; range, 0.8 to 5.8; P less than 0.001). However, the diagnostic usefulness of the spontaneous growth hormone test was inferior to that of the stimulation tests, since it identified only 57 percent of the children with growth hormone deficiency identified by the stimulation tests. In the remaining children with growth hormone deficiency, spontaneous growth hormone levels were within the normal range. Children with idiopathic short stature had a normal mean 24-hour level of growth hormone (3.0 micrograms per liter; range, 1.1 to 6.7). No child in this group had low levels of spontaneous growth hormone secretion. We conclude that the measurement of the spontaneous secretion of growth hormone in prepubertal short children had lower sensitivity and offered no diagnostic advantage over stimulation tests. Our data do not support the routine measurement of spontaneous growth hormone secretion in the diagnosis of growth hormone deficiency.

Effect of gonadotropin secretion rate on the radiosensitivity of the rat luteinizing hormone-releasing hormone neuron and gonadotroph

To test the hypothesis that the functional state of hypothalamic LHRH neurons and pituitary gonadotrophs might alter their radiosensitivity, we determined the experimental conditions under which the gonadotropin response to castration could be impaired by a single dose of cranial irradiation. Single doses of cranial irradiation greater than 2000 rads were lethal to unshielded rats. Shielding of the oropharynx and esophagus allowed the animals to survive doses up to 5000 rads. Doses between 2000 and 5000 rads had no effect on basal gonadotropin levels for as long as 3 months after irradiation. Irradiation caused a dose- and time-dependent impairment, however, in the gonadotropin response to castration. Impairment of the gonadotropin levels of castrate animals occurred in animals that were irradiated either before or after castration. However, rats irradiated in the castrate state showed a decreased susceptibility to irradiation damage. Additionally, stimulation of the pituitary by LHRH agonist (LHRHa) 3 h before irradiation significantly reduced the impairment of gonadotropin secretion 12-20 weeks after irradiation (P less than 0.05). Thus, increased functional activity of the rat hypothalamus or pituitary at the time of irradiation, induced by either castration or acute LHRHa administration, was associated with some protection against the gonadotropin-lowering effect of irradiation. Based upon these data, we hypothesize that stimulation of gonadotropin secretion at the time of therapeutic cranial irradiation in humans might protect against subsequent impairment of gonadotropin secretion.

Blood pressure and body size in precocious puberty

Blood pressure increases with age in normal children. This increase appears to be related to body size. To assess the role of body size as a determinant of blood pressure in precocious puberty, we compared the blood pressure of 81 children with precocious puberty with the blood pressure standards for normal children from the NHLBI Task Force on Blood Pressure Control in Children. Children with precocious puberty had significantly increased blood pressure for chronologic age (p less than 0.05) but generally appropriate blood pressure for height age or weight age. These data are consistent with the hypothesis that increased body size causes the increased blood pressure for chronologic age in children with precocious puberty. Physicians who evaluate such children should assess whether blood pressure is appropriate for height age rather than chronologic age.

Dissociation of adrenarche and gonadarche in precocious puberty and in isolated hypogonadotropic hypogonadism

Adrenarche is a developmental change of the adrenal gland that results in increased secretion of adrenal androgens. This maturational process generally begins several years before activation of the hypothalamic-pituitary-gonadal axis (gonadarche). To study further the relationship between adrenarche and gonadarche, we examined adrenarche in patients with precocious puberty and in patients with isolated hypogonadotropic hypogonadism. Plasma dehydroepiandrosterone, dehydroepiandrosterone sulfate, androstenedione, and cortisol were measured basally and during an infusion of ACTH in 50 children with precocious puberty, 5 patients with isolated hypogonadotropic hypogonadism, 7 preadrenarchal children with constitutional short stature, 44 normal pubertal children, and 40 normal adults. Children with precocious puberty did not have a corresponding advance in the timing of adrenarche. Their basal and ACTH-stimulated adrenal androgen levels were markedly lower than those of normal children matched for pubertal stage (P less than 0.05) and were only slightly greater than those reported for normal children of the same age. Similarly, patients with isolated hypogonadotropic hypogonadism and delayed puberty had no corresponding delay of adrenarche. Their adrenal androgen levels were appropriate for chronological age. Thus, these data provide further support for the hypothesis that adrenarche and gonadarche are independent maturational events controlled by separate mechanisms.

Luteinizing hormone releasing hormone analogue therapy for central precocious puberty. Long-term effect on somatic growth, bone maturation, and predicted height

The long-acting analogue of luteinizing hormone releasing hormone, D-Trp6-Pro9-NEt-LHRH (LHRHa), is effective in the short-term treatment of central precocious puberty. We report the results of two to four years of LHRHa therapy in 27 children with this disorder. Secondary sex characteristics regressed in most patients. Sex steroid levels and basal and LHRH-stimulated gonadotropin levels remained suppressed compared with pretreatment values. Linear growth rates decreased from 11.0 +/- 0.8 (SEM) cm/yr before treatment to 5.7 +/- 0.4 cm/yr at two years of treatment and 3.7 +/- 0.7 cm/yr at four years of treatment. Predicted heights by the Bayley-Pinneau method increased from 156.4 +/- 2.0 cm before treatment to 162.3 +/- 2.3 cm at two years and 163.4 +/- 2.4 cm at three years. Five patients treated for four years had a mean increase in predicted height of 5.5 cm. To date no adverse effects have been observed. However, the ultimate safety of this analogue is not known. We conclude that LHRHa appears to be an effective long-term therapy for central precocious puberty.